In hammermills, grinders or shredders which employ a plurality of hammers which are rotated in a working chamber the particle size is determined by the clearance between the hammers and the fixed and wall parts of the working chamber. It is necessary to maintain a specific particle size when the materials being shredded or comminuted are re-cycled or further processed. Because of severe wear on the hammerheads, it is difficult to maintain the required product particle size for extended periods. The severe wear requires frequent servicing of the hammers which can include rebuilding the hammers in place with a welding process, replacing the worn hammers and rebuilding the used hammers for future use or discarding the worn hammers and installing new ones. These procedures are expensive and result in considerable down time.
In conventional prior art hammermills the hammers are pinned to the rotor arms with no provision to change the position of the hammer with respect to the arm.